89E-3

S. A. IBRAHIM¹, M. M. Salameh¹, C. W. Seo¹, T. S. F. Tse¹, and H. Yang². (1) Food Science & Nutrition Program, North Carolina A&T State Univ., Dept. of Human Environment & Family Sciences, 171-B Carver Hall, Greensboro, NC 27411-1064, (2) Dept. of Human Environment & Family Sciences, North Carolina A&T State Univ., 161 Carver Hall, Greensboro, NC 27411

Enterobacter sakazakii is a bacterium belonging to the family Enterobacteriaceae, which contains a number of bacterial species found in the human and animal gut and the environment. The microorganism has been implicated in outbreaks causing meningitis or enteritis, especially in infants. In the few outbreaks that have been reported between 20% and 50% of the infants who contracted the disease has died. It is, however, only very recently that information on the widespread occurrence of E. sakazakii has become available. Recent publications have demonstrated that this microorganism can be found in a wide variety of foods, water and environments including homes and hospitals. The objective of this study was to determine the acid resisitance of E. sakazakii. Overnight strains of E. sakazakii (ATCC 12868, ATCC 29004, ATCC 29544, ATCC 51329 and three clinical isolates, ES01, ES02 and ES03) were used in this study. The acid resistance of these strains was determined by inoculating 100µl of overnight cultures into BHI broth batches adjusted to pH 2.5, 3.5 and 6.5 using HCl. Inoculated broth samples were then incubated at 37 °C for 24 h. The growth of the bacteria was monitored using spectrophotometer (O.D 610nm) 0, 2, 4, 6, 12, and 24 h. Results showed that all tested strains of E. sakazakii were able to survive in acidified BHI broth with pH 3.5 but not pH 2.5. During the incubation period all strains were able to grow in the acidified BHI broth (pH 3.5) and reached maximum growth within 12hr, Strains were not able to survive in the acidified BHI broth (2.5) as observed by the cell density during the incubation period. These results indicate that E. sakazakii was resistant to moderate acidic pH 3.5 and more sensitive to severe pH 2.5. Our results indicate that E. sakazakii strains are resistant to moderate acidic conditions and therefore could develop resistant to several environmental conditions that could influence their survival in food products during processing.

Session 89E, Food Microbiology: Pathogens
2:00 PM - 5:30 PM, Tuesday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana